The present invention relates to a cruise control apparatus for motor vehicle, and more particularly to an apparatus and method in which position information of a peripheral vehicle around a user's vehicle or a preceding vehicle as the object of follow-up is displayed in a manner superimposed on a road form generated from map information.
In a cruise control apparatus for motor vehicle, it is general that in order to give information of the position and azimuth of a motor vehicle existing in the front, a method using peculiar hardware is employed or the display is provided on a graphics display unit possessed by a navigation device. In the method using the peculiar hardware, the fabrication cost is lowered by employing a system in which lumps such as LED's are continuously arranged so that an interval between a user's vehicle and a front vehicle is printed in accordance with the arranging positions of LED's and corresponding LED's are excited into illumination on the basis of measured relative distance information to inform the user of the relative distance.
On the other hand, in the system in which the display is provided on a graphics display unit such as LCD or CRT possessed by a navigation device or the like, it is general to employ a method in which a virtual straight road is generated and marks indicative of a user's vehicle and a front vehicle and a scale for grasping a relative distance are displayed on the generated virtual straight road. As a further high technique, there is a method in which an image of a running road is produced by an image pickup device such as CCD to extract the outlines of the road therefrom and marks indicative of a user's vehicle and a front vehicle and a scale for grasping a relative distance are displayed on the obtained road form. Also, there is a method which uses a distance measuring device or equipment (DME) using millimeter waves or a laser, that is, a method in which the form of a road is determined from information of a reflected version of a transmitted signal from a guard rail or the like existing in the side of the road and marks indicative of a user's vehicle and a front vehicle and a scale for grasping a relative distance are displayed on the obtained road form.
In a cruise control apparatus for motor vehicle, it is desired that the position of a motor vehicle existing in the front is displayed in a manner superimposed on an actual road form. This is because it is desirable to provide a clarified display as to whether the front vehicle is running on a lane under running of a user's vehicle or on a lane adjacent to the running lane. Such display is desired in the case of a curved road or the like. Further, it is desirable to display such information at a low cost and in a form capable of being easily understood by the user. In order to provide the easily understandable display, it is desirable that information on a display screen is made as simple as possible.
On the other hand, the conventional method using the peculiar hardware has neither means for recognizing the form of a road nor means for displaying it. In the method in which a virtual straight road is generated, an image different from the actual road form is generated so that it is not possible to provide the above-mentioned desirable display in a manner superimposed on the actual road form. The method using the image pickup device has a problem that the outlines of a road are undeterminable under a meteorological condition such as snow or mist as well as a problem that the system becomes high in cost. The method using the distance measuring device for determination of the form of a guard rail or the like to extract the outlines of a road has a problem that the determination of road outlines is difficult for a road which has not a guard rail or the like.